This invention relates to a breathable air delivery system for use with a respirator face mask worn under a worker's protective helmet such as an abrasive blasting helmet. The invention also relates to an exhalation exhaust system for use with such a face mask air delivery system and protective helmet, which system also provides a barrier to the introduction of airborne particulate matter into the system and helmet from ambient atmosphere.
Recently enacted regulations of the Occupational Safety and Health Administration ("OSHA") now require workers in abrasive blasting environments to wear a tight fitting respirator face mask under conditions of exposure to atmospheric contaminants which exceed a minimum level. Usually, when an abrasive blasting helmet is worn, a protective garment is also worn to protect the wearer's body from assault by debris from a blasting activity. Such garments, which are typically in the form of a sleeveless poncho, long sleeve parka or the like have an upper open end which is attachable to and around a lower edge portion of the helmet. A typical abrasive blasting helmet contains a dome portion which covers the worker's head and a cowl portion attached to and around a base of the dome portion so as to depend downwardly to cover the worker's face. The cowl portion contains a viewing lens in a frontal portion thereof and a second removable viewing lens in a visor assembly removably attached to the outer surface of a frontal region of the cowl portion. The inner and outer lenses register with one another when the visor is operatively secured to the helmet. By means of this arrangement, the outer lens protects the inner lens from abrasion and can readily be replaced from time to time as necessary.
But when a respirator face mask is worn on a worker's face under the helmet and the protective garment is also worn with the upper open end being attached to and around the helmet, it is important to provide comfortable and convenient means for supplying breathable compressed air directly to the face mask through or under the protective garment from a remote source which will not be contaminated by debris from a blasting operation. It is also important to provide means for readily exhausting exhaled air from the face mask to ambient atmosphere without, at the same time, introducing ambient air with dust or other contaminates therein from the blasting operation into the helmet region around the wearer's face. While abrasive blasting helmets and protective garments which are releasably attachable thereto are, broadly speaking, well known in the prior art, in a preliminary patent search which we have obtained, we have not found any air delivery and exhalation exhaust systems for such an assembly wherein a respirator face mask is also used.
In U.S. Pat. No. 4,455,687 to S. O. G. Johansson dated Jun. 26, 1984 a protective garment is shown having an upper open end attached to and around the base of a safety helmet. Breathable air is supplied into the helmet along a perforated air hose which emits breathable air into the helmet, but no face mask is used and no means for supplying breathable air to a face mask is shown. A detachable collar-like filter fits about the neck of the helmet through which air may be exhausted from the helmet downwardly into the garment. A problem encountered with this system is that breathable air supplied to the helmet is mixed with exhaled air in the helmet and is exhausted through the filter. Obviously, both fresh air and exhaled air will be exhausted through the filter, which is inefficient. Other prior art protective helmets with attached protective garments which have the same shortcoming are disclosed in U.S. Pat. No. 3,911,914 issued to S. O. G. Johansson on Oct. 14, 1975 and U.S. Pat. No. 4,172,294 issued to Leon J. Harris on Oct. 30, 1979.
In U.S. Pat. No. 1,095,089 issued to H. G. Dinn on Apr. 28, 1914 a hooded protective garment is disclosed wherein breathable compressed air is supplied to the hood through what could be considered a very loosely fitting shoulder supported air hose collar. Breathable air is released into the lower front portion of the hood under the chin of the wearer by a perforated distributor connected in the front of the collar. In addition to having the same shortcoming as previously explained, the loose collar can not function as a barrier to restrain blast debris from entering the hood through the arm openings and base of the garment.
By means of our invention, these and other difficulties encountered with prior art abrasive blasting helmets and attached protective garments are substantially overcome.